This invention relates to an inhalation apparatus for dispensing substances for inhalation and, in particular, but not exclusively, for dispensing medicinal products.
Known dispensing apparatus for use in inhalation apparatus include metered dose inhalers and dry powder inhalers. In known metered dose inhalers, the aerosol stream from a pressurized dispensing container is fired towards a patient or user of the inhaler into an airflow travelling in the same direction. A user inhales through a mouthpiece of the inhaler and creates an airflow through the container from air inlet holes which are generally at a part of the inhaler well spaced from the mouthpiece. Medicament is then released into this airflow at a point between the air inlet holes and the mouthpiece so that it is travelling in the same direction as the airflow. Typically, in such devices, there is no restriction in the airflow between the air inlet holes and the mouthpiece. Because of this, a substantial airflow can be created by the user of the device and, because the medicament is fired into the airflow in the same direction as the airflow, the effect is that particles of medicament can attain quite substantial velocities. As inhalers of this type are normally designed to be as small as practical for the convenience of the user, the distance between the point at which the medicament is fired and the patient""s mouth is usually quite small so that there is little distance for the inertia of the particles of medicament to decrease with the result that the particles may impact in the oropharynx of a user with quite high velocity. This can be a problem with certain medicaments.
In known dry powder inhalers, powdered medicament, which is often combined with a powdered carrier, such as lactose, is stored within a delivery device until delivery of the medicament is required. It is known to store the medicament in a bulk holding reservoir in the delivery device. The drug is removed from the reservoir on an as required basis. It is also known to provide dry powder inhalers wherein the medicament is contained within discrete doses within a dosage unit such as a gelatine capsule. A problem with both types of known dry powder inhaler is that the medicament and carrier can form relatively large particles which when inhaled by the user do not reach deep into the lungs, which has been shown to be necessary for the most advantageous medical result to be obtained. It is known to provide baffle plates within an airflow passageway of a dry powder inhaler such that the medicament and carrier impact on the baffle plates and are, to a degree, separated and the particle size reduced. However, a problem with such baffle plates is that the medicament and carrier only pass through the baffle plates once and, as a result, a significant proportion of larger particles still exit the inhaler and are inhaled by the user.
According to the present invention there is provided inhalation apparatus comprising a housing defining a socket for receiving a pressurized dispensing container, actuator means for receiving a valve stem of the pressurized dispensing container and a cylindrical chamber having an inlet located at a periphery of the chamber and an outlet at or near a center of the chamber, the actuator means defining duct means to direct product dispensed from the valve stem of the pressurized dispensing container through the inlet of the cylindrical chamber in a direction substantially tangential to the major axis of the cylindrical chamber, the outlet of the cylindrical chamber communicating with a mouthpiece, such that inhalation by a user on the mouthpiece creates a cyclonic airflow in the cylindrical chamber between the inlet and outlet in which the dispensed product is entrained for inhalation.
The present invention also provides a method of inhaling product dispensed from a pressurized dispensing container comprising the steps of inhaling on a mouthpiece of an inhalation apparatus comprising a cylindrical chamber having an inlet at a periphery thereof and an outlet at or near a center thereof which communicates with the mouthpiece, to thereby create a cyclonic airflow from the inlet to the outlet, actuating the pressurized dispensing container to dispense a dose of product through the inlet of the cylindrical chamber in a direction substantially tangential to the major axis of the cylindrical chamber such that the product is entrained in the airflow and inhaled through the mouthpiece.